I have an asp.net core web app, and I'm trying to use the UmbracoCms.Headless.Client and UmbracoCms.Headless.Client.Web packages, and I am getting an error whenever I try and use the PublishedContentService.

I have a very, very, simple controller, with a single action that is calling the service and getting the items at the site root.

[HttpGet("[action")]
publis async Task<IEnumerable<ContentItem>> GetSiteTree()
{
    var content = await publishedContentService.GetRootContent();

    return content;
}

However, the service throws an exception stating "The remote certificate is invalid according to the validation procedure." Which doesn't make any sense, I can access the site in the browser and in Postman via https, but when I try from code, I get this issue.

I have tried creating a fresh console application in a brand new solution and installing the packages, with the same result.

Has anyone else seen this issue when trying to use headless in code? If so, is there a known solution?

I am using asp.net core 2.1.1 and headless version 0.9.7-CI20180905-01.